The present invention is directed, in general, to wireless networks and, more specifically, to a system for controlling power consumption in an wireless mobile station by changing between slotted mode operation and non-slotted mode operation.
Reliable predictions indicate that there will be over 300 million cellular telephone customers worldwide by the year 2000. Within the United States, cellular service is offered by cellular service providers, by the regional Bell companies, and by the national long distance operators. The enhanced competition has driven the price of cellular service down to the point where it is affordable to a large segment of the population. In addition to cellular telephones, consumers use a wide variety of other wireless communication devices that communicate with base stations that are part of a wireless network.
Mobile stations, such as cellular telephones, PCS handset devices, portable computers, telemetry devices, and the like, frequently operate from an external power source connected to the mobile station, with an internal battery supply being available to provide a limited period of operation without the external power source. Mobile stations which provide more extended intervals of battery back-up operation offer increased value of service to users and competitive advantages for service providers.
Typically, mobile station battery operation is extended through the use of techniques which lower the amount of required power when the mobile station is in an idle state and not transferring voice or data traffic. A mobile station may enable one or more power saving configurations when it is in the idle state. For instance, the mobile station may disable its transmitter during the idle state, decreasing the amount of power required for idle state operation. A mobile station may further reduce its idle state power requirements by enabling a slotted mode of operation with a base station.
A mobile station enters the idle state when the mobile station is turned ON, is synchronized with the system, and has no calls in progress. During the idle state, a mobile station actively listens to a paging channel for information which includes overhead messages, such as system parameter messages, as well as messages directly addressed to the mobile station from a base station. A mobile station may be operating on battery or an external power source when it is in the idle state.
During the idle state, the mobile station may communicate with a base station in a non-slotted or slotted mode. A typical paging channel slot is an 80 millisecond time slot within a paging slot cycle, with a slot cycle ranging from 16 to 2048 time slots. In the non-slotted mode, the mobile station monitors all paging channel slots for messages from the base station. In the slotted mode, the mobile station only monitors a selected subset of the paging channel slots for messages from the base station. The remainder of the time, power is turned OFF to the receiver circuits in the mobile station in order to save power. A mobile station extends the battery supply operating life by entering a slotted mode of operation with the base station because the mobile station receiver consumes power only during selected slot cycles rather than across the entire paging cycle.
Unfortunately, slotted mode of operation decreases the rate at which messages can be received by the mobile station. Each message may be divided across multiple time slots during slotted mode of operation. This can be detrimental when the mobile station is moving rapidly from the coverage area of a first base station to the coverage area of a second base station, because a handoff message may not properly be received before the mobile station has moved too far away from the first base station. As a result, a communication link may be dropped and the mobile station must reacquire another base station. A user is typically unaware of slotted mode of operation, because the mobile station is frequently configured to enter slotted mode automatically in order to prolong battery life. This is true even when the mobile station is connected to an external power supply.
Therefore, there exists a need for improved wireless devices that are less susceptible to losing a communication to a base station due to prolonged slotted mode. In particular, there is a need in the art for improved wireless devices capable of automatically terminating slotted mode operation when it is not needed.
To address the above-discussed deficiencies of the prior art, it is a primary object of the present invention to provide, for use in a wireless communication device capable of communicating with a base station of a wireless network in a slotted mode of operation and in a non-slotted mode of operation, an apparatus capable of controlling the slotted mode of operation and the non-slotted mode of operation. In an advantageous embodiment of the present invention, the apparatus comprises: 1) a power monitor capable of determining if an external power supply is providing external power to the wireless communication device and generating a first signal indicating whether external power is being provided; and 2) a slotted mode power controller coupled to the power monitor and capable of receiving the first signal, wherein the slotted mode power controller is capable of terminating the slotted mode of operation whenever the first signal indicates that the external power is being provided.
According to one embodiment of the present invention, the slotted mode power controller terminates the slotted mode of operation by communicating with the base station to establish a non-slotted mode of operation.
According to another embodiment of the present invention, the power monitor monitors an external power supply interface circuit capable of receiving the external power.
According to still another embodiment of the present invention, the power monitor modifies a value of the first signal according to whether the external power supply is receiving the external power.
According to yet another embodiment of the present invention, the slotted mode power controller is capable of re-establishing the slotted mode of operation whenever the first signal indicates that the external power is not being provided.
According to a further embodiment of the present invention, the external power supply interface is used to charge an internal battery power supply in the wireless communication device.
According to a still further embodiment of the present invention, the power monitor is capable of measuring a power level provided by the external power supply.
According to a yet further embodiment of the present invention, the power monitor is capable of determining if the measured power level is below a minimum threshold power level, and in response to a determination that the measured power level is below the minimum threshold power level modifying the first signal to indicate that the external power is not being provided.
The foregoing has outlined rather broadly the features and technical advantages of the present invention so that those skilled in the art may better understand the detailed description of the invention that follows. Additional features and advantages of the invention will be described hereinafter that form the subject of the claims of the invention. Those skilled in the art should appreciate that they may readily use the conception and the specific embodiment disclosed as a basis for modifying or designing other structures for carrying out the same purposes of the present invention. Those skilled in the art should also realize that such equivalent constructions do not depart from the spirit and scope of the invention in its broadest form.
Before undertaking the DETAILED DESCRIPTION OF THE INVENTION, it may be advantageous to set forth definitions of certain words and phrases used throughout this patent document: the terms xe2x80x9cincludexe2x80x9d and xe2x80x9ccomprise,xe2x80x9d as well as derivatives thereof, mean inclusion without limitation; the term xe2x80x9cor,xe2x80x9d is inclusive, meaning and/or; the phrases xe2x80x9cassociated withxe2x80x9d and xe2x80x9cassociated therewith,xe2x80x9d as well as derivatives thereof, may mean to include, be included within, interconnect with, contain, be contained within, connect to or with, couple to or with, be communicable with, cooperate with, interleave, juxtapose, be proximate to, be bound to or with, have, have a property of, or the like; and the term xe2x80x9ccontrollerxe2x80x9d means any device, system or part thereof that controls at least one operation, such a device may be implemented in hardware, firmware or software, or some combination of at least two of the same. It should be noted that the functionality associated with any particular controller may be centralized or distributed, whether locally or remotely. Definitions for certain words and phrases are provided throughout this patent document, those of ordinary skill in the art should understand that in many, if not most instances, such definitions apply to prior, as well as future uses of such defined words and phrases.